Question

A ball is thrown straight down at 10.0 m/s from a 38.4 m-high building. How long does it take to reach the ground?

Answer 1

Ball will take 1.9591 sec to reach the ground

Step-by-step explanation:

We have given initial velocity of the ball u = 10 m/sec

Height from which ball is thrown h = 38.4 m

Acceleration due to gravity
`g=9.8m/sec^2`

From second equation of motion we know that
`h=ut+(1)/(2)gt^2`

`38.4=10t+4.9t^2`

`4.9t^2+10t-38.4=0`

After solving equation for t

t= -4 sec and t = 1.9591 sec

As time can not be negative so time will be 1.9591 sec